The behavior of loose anisotropically consolidated calcareous sand obtained from an island in the South China Sea was investigated under undrained monotonic and cyclic loading in a hollow cylinder torsional apparatus. The tests were conducted on specimens which consolidated under various initial effective confining pressures and consolidation stress ratios. The monotonic test results show that the failure and phase transformation line are essentially independent of the consolidation conditions, while the initial contractive tendency of the specimens decreases with an increasing consolidation stress ratio. During monotonic loading of the anisotropically consolidated specimens, a same major principal stress direction is observed at the constant stress ratio lines up to the phase transformation line, irrespective of initial effective confining pressure. The cyclic strength of the sand increases with an increasing consolidation stress ratio. Moreover, a pronounced stress dependence is observed in the sand with higher consolidation stress ratio. During cyclic loading, the generated excess pore water pressure presents considerable fluctuations. The normalized terminal excess pore water pressure is described as a function of consolidation stress ratio. The tests show that the particle shape, rather than particle crushing, plays an important role in the monotonic and cyclic behaviors of the calcareous sand.

Hollow cylinder torsional shear tests on loose isotropically and anisotropically consolidated calcareous sand were conducted to investigate the cyclic behavior under three different linear stress paths, including horizontal line, oblique line, and vertical line stress paths, in a coordinate system of the normal stress difference and the horizontal shear stress. The dominant strain components of the isotropically consolidated specimens are affected by the stress paths. With increasing consolidation stress ratio, axial strain gradually becomes the dominant strain component under the three different stress paths. The cyclic strength of the isotropically consolidated specimens under the three different stress paths are almost the same, while for the anisotropically consolidated specimens, the cyclic strengths are strongly affected by the stress paths. These results indicate that conventional cyclic triaxial tests may overestimate cyclic strength in some cases. Irrespective of the stress paths and cyclic stress ratios, the terminal residual excess pore pressure ratio decreases with increasing consolidation stress ratio. Moreover, an empirical equation is proposed to describe the relationship between the normalized shear work and the normalized residual excess pore pressure ratio. The comparative study reveals that the relationship proposed for silica sand is not suitable for the dynamic analyses of calcareous sand.

Large-diameter cast-in-place concrete pipe (PCC) pile is widely used for pile foundation and pile-supported embankment over soft clay in China. However, studies on PCC pile-soil reactions (p-y curves) or performance of the pile groups under lateral load are not widely reported. A large-scale model test of a single PCC pile under lateral load is carried out, and its lateral bearing capacity, bending moment, and p-y curves are measured and analyzed. The deflection and bending moment of this PCC pile is calculated by the p-y curves method and modified pile modulus using LPILE software. Three-dimensional numerical analyses are conducted using ABAQUS software. The reliability and accuracy of the numerical simulation model are verified by comparing the results of the large-scale model test with the LPILE calculation. The distribution of deflection and bending moment along the pile and pile group efficiencies of the PCC piles are comparatively analyzed with those of a drilled shaft, which has the same co...

This paper presents the findings from both the detailed site investigations and the computational analyses on the Zipingpu concrete-faced rockfill dam (CFRD), a 156-m high dam in which 100-cm permanent settlement and 60-cm horizontal displacement occurred during the 2008 Wenchuan, China, earthquake. The Zipingpu CFRD was 17 km away from the epicenter and was considerably damaged by the Wenchuan earthquake. It was estimated that the peak acceleration in the top of the dam along the axial and vertical direction was about 20.0 m/s2, and the peak acceleration at the river level was about 16.0 m/s2. It was calculated that peak acceleration of dam bedrock was more than 5.0 m/s2, and the intensity (Chinese scale) was more than IX. Based on an in-situ investigation, the peak value of settlement of the dam crest reached 744.3 mm, and the peak value of horizontal displacement toward the right and left abutment are 226.1 mm and 106.8 mm, respectively. The actual experience of the peak acceleration and sei...

The strength and dilatancy behaviors of modeled dense rockfill material were systematically investigated through a series of true triaxial compression tests at different minor principal stress and intermediate principal stress ratios. It was found that the intermediate principal stress ratio had great influence on the critical-state friction angle, peak-state friction angle, and maximum dilatancy of the modeled rockfill material. Both the critical-state and peak-state friction angles at a given confining pressure first increased and then decreased with an increase in the intermediate principal stress ratio. An increase in the minor principal stress led to a decrease in both the critical-state and peak-state friction angles at a given intermediate principal stress ratio. The maximum dilatancy decreased with an increase in the minor principal stress or the intermediate principal stress ratio. It was also found that the intermediate principal stress ratio significantly affected the relationship betwe...